The present invention relates generally to a method for generating and viewing images. More specifically, the present invention relates to a method for generating and viewing full-surround, e.g., spherical, image data.
Systems and techniques for changing the perspective of a visible image in producing a resultant image, and systems and methods of transforming an image from one perspective form to another have been the subject of scientific thought and research for many years. Systems and techniques for transforming visible images can generally be divided into three separate categories:
(1) perspective generation systems and methods suitable for applications such as flight simulators; PA1 (2) three-dimensional (3D) to two-dimensional (2D) conversion systems and methods; and PA1 (3) miscellaneous systems and methods.
The first category includes U.S. Pat. No. 3,725,563, which discloses a method of and apparatus for raster scan transformations using rectangular coordinates which are suitable for electronically generating images for flight simulators and the like. More specifically, the '563 patent discloses a technique for raster shaping, whereby an image containing information from one viewpoint is transformed to a simulated image from another viewpoint. Also in this category, U.S. Pat. No. 4,763,280 discloses a curvilinear dynamic image generation system for projecting rectangular coordinate images onto a spherical display surface. In the disclosed system, rectangular coordinates are converted to spherical coordinates and then the spherical coordinates are distorted for accomplishing the desired simulation of curvature.
The second category of systems and techniques perform 3D-to-2D conversion, or vice versa. For example, U.S. Pat. No. 4,821,209 discloses a method of and apparatus for data transformation and clipping in a graphic display system, wherein data transformation is accomplished by matrix multiplication. Also in this second category, U.S. Pat. No. 4,667,236 discloses a television perspective effects system for providing perspective projection whereby each point of a three-dimensional object is projected onto a two-dimensional plane. New coordinates X' and Y' are derived from the original coordinates X, Y and Z, and the viewing distance D, using the general formulas X'=XD/Z and Y'=YD/Z. As the object to be displayed is rotated around the X or Y axis, the viewing distance D is changed for each point.
In the third category, miscellaneous systems and methods are disclosed by, for example, U.S. Pat. No. 5,027,287, which describes a device for the digital processing of images to obtain special geometrical effects wherein digital image data corresponding to intersection points on a rectangular X, Y grid are transposed by interpolation with respect to intersection points of a curved surface. The third category also includes U.S. Pat. No. 4,882,679, which discloses a system and associated method of reformatting images for three-dimensional display. The disclosed system is particularly useful for generating three-dimensional images from data generated by diagnostic equipment, such as magnetic resonance imaging equipment.
However, none of the above described methods or systems permit viewing in circular perspective, which is the best way to view spherical data. Circular perspective provides all that linear perspective does when zoomed in, but it allows the viewer to zoom out to the point where the viewer can see substantially everything in the spherical image data simultaneously in a visually palatable and coherent way.
Moreover, it is often difficult to generate the needed spherical image data set for input to a viewing method or corresponding viewing system. In the field of photography, cameras are often fitted with a variety of wide angle lenses so that still photographs of panoramic views can be taken. In addition, digital image processing has made possible the creation of computer generated images of panoramic views from multiple digital images which are, in turn, derived from pictures taken using cameras fitted with conventional lenses.
Each computer generated image is created by digitally stitching the multiple digital images together using software. However, it is difficult to create a seamless computer image from digital images which are derived from analog-based pictures taken using conventional photography techniques, primarily because it is practically impossible to properly align the camera, which is used to take those pictures, between exposures.
Early attempts at digital image processing have produced computer generated images of panoramic views which are cylindrical in nature. In other words, the computer images generated using conventional digital image processing techniques do not provide any views which are either above or below the camera that produced the original analog based pictures from which the digital images are derived.
With the advent of new digital image processing techniques, software has been developed which allows for the transformation of 360 degrees of visual input data in accordance with a particular perspective. The inventor of the present invention recognized a need for devices and methods of taking pictures which capture 360 degrees of spherical visual input data in order to take advantage of the newly developed digital image processing techniques which have been implemented in software. By way of example, one such software algorithm is described in U.S. Pat. No. 5,684,937, by the inventor of the present invention.
What is needed is a method for generating a full-surround, e.g., spherical, data set and subsequently viewing that data set in circular perspective. What is also needed is a method for viewing a spherical image data set in circular perspective which is computationally simple. Preferably, the method for viewing the spherical image data set in circular perspective can be employed on any personal computer (PC) system possessing a three dimensional (3-D) graphics capability.